HYDROTREATMENT PROCESS USING A SEQUENCE OF CATALYTIC CONVERTERS WITH A CATALYTIC CONVERTER BASED ON NICKEL AND TULRAM ON A SILICON DIOXIDE-ALUMINUM OXIDE SUPPORT

Description

technical field

[0001] The invention relates to a hydrotreating process for a hydrocarbon feedstock using a sequence of at least two specific catalysts. The objective of the process is the production of hydrodesulfurized, hydrodeazurized, and hydrodearomatized hydrocarbon feedstocks.

[0002] Conventional hydrotreating catalysts typically comprise an oxide support and an active phase based on group VIB and VIII metals in their oxide forms, along with phosphorus. The preparation of these catalysts generally involves impregnating the support with the metals and phosphorus, followed by drying and calcination to obtain the active phase in its oxide forms. Before use in a hydrotreating and / or hydrocracking reaction, these catalysts are usually subjected to sulfidation to form the active species.

[0003] The addition of an organic compound to hydrotreating catalysts to improve their activity has been recommended by those skilled in the art, particularly for catalysts prepared by impregnation followed by drying without subsequent calcination. These catalysts are often referred to as "additized dried catalysts".

[0004] Usually, a hydrotreating catalyst for hydrocarbon cuts aims to eliminate the sulfur, nitrogen or aromatic compounds contained in them in order to bring, for example, a petroleum product to the required specifications (sulfur content, aromatic content etc...) for a given application (motor fuel, gasoline or diesel, domestic fuel oil, jet fuel).

[0005] Due to increasingly stringent air quality legislation in many countries, ongoing efforts are underway to develop more efficient catalysts and processes for the production of ultra-low sulfur fuels. While significant progress has been made in developing effective catalysts for these processes, major challenges remain, such as their limited aromatic hydrocarbon saturation activity or hydrodeazotation performance.

[0006] Reducing sulfur, nitrogen, and aromatic content is therefore a desired outcome in the pretreatment stage for hydrocracking or fluidized bed catalytic cracking (FCC) processes to improve performance in subsequent hydrocracking or FCC stages. These processes typically handle feedstocks with high sulfur, nitrogen, and aromatic content.

[0007] However, a hydrotreating catalyst optimized for hydrodesulfurization (HDS) is not automatically optimized for aromatic saturation (or hydrodearomatization HDA) or for hydrodeazotation (HDN), and vice versa. Therefore, catalyst sequences are often used, in which each catalyst is optimized for a specific type of hydrotreating process.

[0008] Such supported catalyst sequences are described for example in documents US2011 / 0079542, US5068025, CN1176290, FR3013720 or FR3013721.

[0009] There are also unsupported catalyst chains, also called "bulk" catalysts according to Anglo-Saxon terminology and known for example from documents US7816299 or CN102851070. The supported catalyst chain, however, has the advantage of using regenerable catalysts which are also less expensive (because they have a lower metal content) and which are also active with a lower metal content.

[0010] US2003 / 0116473 discloses a hydrotreating process using a sequence of a molybdenum-based supported catalyst followed by a tungsten-based supported catalyst. This document does not disclose the volumetric distribution of the two catalytic zones.

[0011] Document CN105435824 discloses a hydrotreating process using a sequence of a citric acid-additized CoMoP supported catalyst followed by a NiMoWP supported catalyst. The volume of the first catalyst is between 5 and 95%, and the volume of the second catalyst is between 95 and 5%. An increase in HDS and HDN is observed.

[0012] Regardless of the catalyst sequence chosen, the resulting modifications do not always sufficiently increase the performance of the catalytic system to meet the specifications regarding the sulfur, nitrogen, and / or aromatic content of fuels. Consequently, it is essential for refiners to find new hydrotreating processes with improved performance in terms of activity and stability.

[0013] The applicant has developed a hydrotreating process for a hydrocarbon feedstock comprising bringing said feedstock into contact with a specific sequence of catalysts enabling the overall activity and overall stability of the process to increase. Summary

[0014] The invention relates to a hydrotreating process for a hydrocarbon feedstock as described in the attached claims.

[0015] The applicant has surprisingly discovered that a sequence of a first hydrotreating reaction section containing a first catalyst based on an active phase consisting of nickel and molybdenum on an alumina support and a second hydrotreating reaction section containing a second catalyst based on an active phase consisting of nickel and tungsten on a more acidic support in the presence of phosphorus and an organic compound presents a synergistic effect in terms of activity and stability in hydrotreating, particularly in aromatic hydrogenation (HDA) but also in hydrodeazotation (HDN) and / or hydrodesulfurization (HDS).

[0016] Indeed, the choice of the right active phase, a suitable support, the presence of phosphorus and / or an organic compound for each catalyst allows us to observe a symbiosis of the first catalyst based on an active phase made up of nickel and molybdenum on a non-acidic or slightly acidic support (alumina), carrying out in particular the HDS and part of the HDN, followed by the second catalyst based on an active phase made up of nickel and tungsten in the presence of phosphorus and an organic compound on a more acidic support (silica-alumina), allowing the modification of the structure of the most refractory aromatic compounds (by isomerization reactions and / or cracking), making these molecules more reactive, thus promoting the HDA prerequisite to increase the HDN, in particular thanks to the tungsten which provides a gain in hydrogenating activity.

[0017] On the one hand, the second catalyst is highly active, particularly in HDA and HDN, which allows it to complete the hydrotreating reactions, especially HDS and HDN, of the first catalyst necessary to meet specifications. Similarly, stability is increased because the cycle time is extended thanks to the temperature reduction required for the HDS, HDN, and HDA reactions.

[0018] On the other hand, the second catalyst deactivates less quickly, which makes it possible to increase the cycle time on a standard load or to allow the treatment of loads heavily loaded with sulfur, nitrogen and / or aromatics.

[0019] The hydrotreating process according to the invention is particularly suitable for vacuum distillate feedstocks. The hydrotreating process according to the invention is also particularly suitable for hydrotreating feedstocks containing high levels of nitrogen and aromatics, such as feedstocks from catalytic cracking, coker, or visbreaking.

[0020] The process according to the present invention makes it possible to produce a hydrotreated hydrocarbon cut, that is to say, one free of nitrogen compounds, sulfur compounds, and most aromatic compounds. Preferably, according to the process of the invention, the conversion to hydrodesulfurization (HDS) is greater than 95%, preferably greater than 98%. Preferably, according to the process of the invention, the conversion to hydrodeazotation (HDN) is greater than 90%, preferably greater than 95%. Preferably, according to the process of the invention, the conversion to aromatic hydrogenation (HDA) is greater than 35%, preferably greater than 40%.

[0021] According to one variant, said first hydrotreating reaction section containing the first catalyst occupies a volume V1, and said second hydrotreating reaction section containing the second catalyst occupies a volume V2, the distribution of volumes V1 / V2 being between 50%vol / 50%vol and 90%vol / 10%vol respectively.

[0022] The volumetric distribution of the two catalysts, in particular the fact that the second reaction section containing the second catalyst occupies a smaller volume than the first reaction section containing the first catalyst, allows the HDS, HDN and HDA reactions carried out in the first or second reaction section to be optimized in order to obtain hydrocarbon cuts to specifications while increasing the activity and stability of the catalytic system compared to a system containing only one of the catalysts.

[0023] According to one variant, the distribution of volumes V1 / V2 is between 70%vol / 30%vol and 80%vol / 20%vol respectively of said first and second hydrotreating reaction section.

[0024] The second catalyst is characterized in that: the nickel content, expressed as NiO, is between 1.3 and 4.3% by weight relative to the total weight of the catalyst, the tungsten content, expressed as WO3, is between 17 and 31% by weight relative to the total weight of the catalyst, the phosphorus content, expressed as P2O5, is preferably between 1.3 and 3.4% by weight relative to the total weight of the catalyst.

[0025] The second catalyst is further characterized in that: the Ni / W molar ratio is between 0.18 and 0.45 mol / mol, the P / W molar ratio is between 0.18 and 0.45 mol / mol.

[0026] According to one variant, the silica content in the support of the second catalyst is between 10 and 50% wt. relative to the total weight of the support.

[0027] The first catalyst has a molybdenum content of between 5 and 40 wt%, expressed as MoO 3, relative to the total weight of the catalyst and a nickel content of between 1 and 10 wt%, expressed as NiO, relative to the total weight of the catalyst.

[0028] The first catalyst further comprises phosphorus at a content of between 0.1 and 20 wt% expressed as P₂O₅ relative to the total weight of the catalyst. In one variant, the first catalyst further contains an organic compound containing oxygen and / or nitrogen and / or sulfur.

[0029] According to one variant, the organic compound is chosen from a compound containing one or more chemical functions selected from among a carboxylic acid, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, amide, or compounds including a furanite ring or a sugar, and preferably it is chosen from γ-valerolactone, 2-acetylbutyrolactone, triethylene glycol, diethylene glycol, ethylene glycol, ethylenediaminetetraacetic acid (EDTA), maleic acid, malonic acid, citric acid, acetic acid, oxalic acid, gluconic acid, glucose, fructose, sucrose, sorbitol, xylitol, γ-ketovaleric acid, a C1-C4 dialkyl succinate, and more particularly dimethyl succinate, dimethylformamide, 1-methyl-2-pyrrolidinone, propylene carbonate, 2-methoxyethyl 3-oxobutanoate, bicine, tricine,2-Furaldehyde (also known as furfural), 5-Hydroxymethylfurfural, 2-Acetylfuran, 5-Methyl-2-furaldehyde, ascorbic acid, butyl lactate, ethyl lactate, butyl butyryllactate, ethyl 3-Hydroxybutanoate, ethyl 3-Ethoxypropanoate, 2-Ethoxyethyl acetate, 2-Butoxyethyl acetate, 2-Hydroxyethyl acrylate, 1-Vinyl-2-pyrrolidinone, 1,3-Dimethyl-2-imidazolidinone, 1,5-Pentanediol, 1-(2-Hydroxyethyl)-2-pyrrolidinone, 1-(2-Hydroxyethyl)-2,5-pyrrolidinedione, 5-Methyl-2(3H)-furanone, 1-Methyl-2-piperidinone, 4-aminobutanoic acid, butyl glycolate, ethyl 2-mercaptopropanoate, ethyl 4-oxopentanoate, diethyl maleate, dimethyl maleate, dimethyl fumarate, diethyl fumarate, dimethyl adipate, and dimethyl 3-oxoglutarate.

[0030] According to one variant, the organic compound content is between 1 and 30% by weight relative to the total weight of the catalyst.

[0031] According to one variant, the first and / or second catalyst is at least partially sulfided.

[0032] According to one variant, the hydrotreating process is implemented as a pretreatment in a fluidized bed catalytic cracking process.

[0033] According to one variant, the hydrotreating process is implemented as a pretreatment in a hydrocracking process. Detailed description of the invention Definitions

[0034] According to the present invention, the expressions "between ... and ..." and "between ... and ..." are equivalent and mean that the limit values ​​of the interval are included within the described range of values. If this were not the case and the limit values ​​were not included within the described range, this clarification will be provided by the present invention.

[0035] In the sense of the present invention, the different parameter ranges for a given step, such as pressure ranges and temperature ranges, can be used alone or in combination. For example, in the sense of the present invention, a preferred pressure range can be combined with a more preferred temperature range.

[0036] In the following, specific and / or preferred embodiments of the invention may be described. They may be implemented separately or in combination, without limitation as to whether they can be combined, when technically feasible.

[0037] According to the present invention, pressures are absolute pressures, also noted as abs., and are given in absolute MPa (or abs. MPa), unless otherwise indicated.

[0038] In what follows, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC Press, editor-in-chief DR Lide, 81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals in columns 8, 9, and 10 according to the new IUPAC classification.

[0039] Specific surface area refers to the specific surface area BET (S BET in m² / g) determined by nitrogen adsorption in accordance with ASTM D 3663-78, based on the Brunauer-Emmett-Teller method described in the periodical "The Journal of American Society", 1938, 60, 309.

[0040] The total pore volume of the catalyst or the support used for catalyst preparation is defined as the volume measured by mercury porosimeter intrusion according to ASTM D4284-83 at a maximum pressure of 4000 bar (400 MPa), using a surface tension of 484 dyne / cm and a contact angle of 140°. The wetting angle was taken to be 140° following the recommendations of the book "Techniques de l'ingénieur, traité analyse et caractérisation" (Engineering Techniques, Analysis and Characterization Treatise), pages 1050-1055, by Jean Charpin and Bernard Rasneur. To obtain greater accuracy, the total pore volume value corresponds to the value of the total pore volume measured by mercury porosimeter intrusion on the sample minus the value of the total pore volume measured by mercury porosimeter intrusion on the same sample at a pressure of 30 psi (approximately 0.2 MPa).

[0041] The metal content of group VIII and group VIB is measured by X-ray fluorescence.

[0042] The contents of Group VIB metal, Group VIII metal, and phosphorus in the catalyst are expressed as oxides after correction for loss on ignition of the catalyst sample at 550°C for two hours in a muffle furnace. Loss on ignition is due to the loss of volatile compounds and is determined according to ASTM D7348.

[0043] Hydrotreatment refers to reactions including hydrodesulfurization (HDS), hydrodeazotation (HDN) and aromatic hydrogenation (HDA). The charge

[0044] The feedstock used in the hydrocracking process according to the invention is a hydrocarbon feedstock in which at least 50% by weight of the compounds have an initial boiling point above 300°C and a final boiling point below 650°C, preferably in which at least 60% by weight, preferably in which at least 75% by weight, and more preferably in which at least 80% by weight of the compounds have an initial boiling point above 300°C and a final boiling point below 650°C. Said feedstocks preferably have a T5 boiling point above 300°C, preferably above 340°C, meaning that 95% of the compounds present in the feedstock have a boiling point above 300°C, and preferably above 340°C.

[0045] A wide variety of feedstocks can be treated by the hydrocracking processes according to the invention. The hydrocarbon feedstock is advantageously chosen from among HCOs (Heavy Cycle Oil according to Anglo-Saxon terminology (heavy gas oils from a catalytic cracking unit)), vacuum distillates, for example gas oils from the direct distillation of crude oil or from conversion units such as catalytic cracking, coker or visbreaking, feedstocks from aromatic extraction units, lubricating oil bases or from the solvent dewaxing of lubricating oil bases, distillates from desulfurization or hydroconversion processes in fixed bed or bubbling bed of atmospheric residues and / or vacuum residues and / or deasphalted oils, or the feedstock may be a deasphalted oil or include vegetable oils or even come from the conversion of feedstocks from biomass.It can also be paraffins produced by the Fischer-Tropsch process. The hydrocarbon feedstock treated according to the hydrocracking process of the invention can also be a mixture of the aforementioned feedstocks. Preferably, the feedstock is a vacuum distillate.

[0046] The charges which are processed, and in particular those mentioned above, generally contain heteroatoms such as sulfur, oxygen and nitrogen and, for heavy charges, they most often also contain metals.

[0047] The nitrogen content of the feeds treated in the processes according to the invention is generally greater than 500 ppm by weight, preferably between 500 and 10000 ppm by weight, more preferably between 700 and 4000 ppm by weight and even more preferably between 1000 and 4000 ppm by weight.

[0048] The sulfur content of the feeds treated in the processes according to the invention is generally between 0.01 and 5% by weight, preferably between 0.2 and 4% by weight and even more preferably between 0.5 and 3% by weight.

[0049] The hydrocarbon filler may optionally contain metals, in particular nickel and vanadium. The cumulative nickel and vanadium content of the hydrocarbon filler is preferably less than 50 ppm by weight, more preferably less than 25 ppm, and even more preferably less than 10 ppm.

[0050] The said hydrocarbon feedstock may optionally contain asphaltenes. The asphaltene content of said hydrocarbon feedstock is generally less than 3000 ppm, preferably less than 1000 ppm, and even more preferably less than 200 ppm.

[0051] The hydrocarbon filler may contain resins. The resin content may exceed 1 wt%, and in particular, 5 wt%. The resin content is measured according to ASTM D 2007-11. The hydrocarbon filler may also contain very little resin (less than 1 wt%).

[0052] The hydrocarbon charge can be of any chemical nature, that is to say, apart from the aromatic content described below, it can have any distribution among the different chemical families chosen from among paraffins, olefins and naphthenes.

[0053] The aromatics content in the feed is greater than or equal to 20% by weight, preferably between 25 and 90% by weight, and more preferably between 30 and 80% by weight. The aromatics content is determined according to the method described in the publication by Burdett RA, Taylor LW and Jones LC, Journal of Molecular Spectroscopy, Rept. Conf., Inst. Petroleum, London 1954, 30-41 (Pub. 1955). Implementation of the process and operating conditions

[0054] The process according to the invention can be carried out in one, two or more reactors. It is generally carried out in a fixed bed.

[0055] When the process according to the invention is carried out in two reactors, step a) can be performed in the first reactor containing the first reaction section through which the feed passes, and then step b) can be performed in the second reactor containing the second reaction section, located downstream of the first reactor. Optionally, the effluent from step a) exiting the first reactor can be subjected to a separation step to separate a light fraction containing, in particular, the H₂S and NH₃ formed during hydrotreating in step a) from a heavy fraction containing the partially hydrotreated hydrocarbons. The heavy fraction obtained after the separation step is then introduced into the second reactor to carry out step b) of the process according to the invention. The separation step can be carried out by distillation, flash separation, or any other method known to those skilled in the art.

[0056] When the process is carried out in a single reactor, step a) is carried out in a first zone containing the first reaction section, and step b) is carried out in a second zone containing the second reaction section downstream of the first zone.

[0057] Said first hydrotreating reaction section containing the first catalyst occupies a volume V1, and said second hydrotreating reaction section containing the second catalyst occupies a volume V2, the distribution of volumes V1 / V2 being generally between 50%vol / 50%vol and 90%vol / 10%vol, preferably between 60%vol / 40%vol and 85%vol / 15%vol and particularly preferably between 70%vol / 30%vol and 80%vol / 20%vol, respectively of said first and second hydrotreating reaction sections.

[0058] The volumetric distribution of the two catalysts, specifically the fact that the second reaction section containing the second catalyst occupies a smaller volume than the first reaction section containing the first catalyst, optimizes the HDS, HDN, and HDA reactions carried out in the first or second reaction section. Indeed, a second catalyst volume that is too large prevents the quantitative removal of nitrogen compounds, thus inhibiting the HDA reaction. Conversely, a second catalyst volume that is too small prevents the HDA reaction from being maximized.

[0059] The operating conditions used in steps a) or b) of the hydrotreating process according to the invention are generally as follows: the temperature is advantageously between 180 and 450°C, and preferably between 250 and 440°C; the pressure is advantageously between 0.5 and 30 MPa, and preferably between 1 and 18 MPa; the hourly volumetric velocity is advantageously between 0.1 and 20 h⁻¹, and preferably between 0.2 and 5 h⁻¹. The hourly volumetric velocity (HVV) is defined here as the ratio of the hourly volumetric flow rate of the hydrocarbon feed to the volume of catalyst(s). The hydrogen / feed ratio, expressed as the volume of hydrogen measured under standard temperature and pressure conditions, per volume of liquid feed, is advantageously between 50 L / L and 5000 L / L, and preferably between 80 and 2000 L / L.

[0060] The operating conditions may be identical or different in steps a) and b). Preferably, they are identical. Composition of the catalysts used in the invention

[0061] According to the invention, the hydrotreating process employs a sequence of a first catalyst comprising an alumina support and an active phase consisting of nickel and molybdenum, and optionally phosphorus and / or an organic compound, and a second catalyst comprising a silica-alumina based support and an active phase consisting of nickel and tungsten, phosphorus and an organic compound. First catalyst

[0062] The first catalyst comprises an alumina support and an active phase consisting of nickel, molybdenum and phosphorus.

[0063] It may also include an organic compound, and possibly boron and / or fluorine.

[0064] The hydrogenating function of said first catalyst, also called the active phase, is ensured by nickel and molybdenum.

[0065] Preferably, the total nickel and molybdenum content is advantageously greater than 6% by weight expressed as oxide relative to the total weight of the catalyst.

[0066] The molybdenum content, expressed as MoO3, is between 5 and 40% by weight, preferably between 8 and 39% by weight, and more preferably between 10 and 38% by weight relative to the total weight of the catalyst.

[0067] The nickel content, expressed as NiO, is between 1 and 10% by weight, preferably between 1.5 and 9% by weight, and more preferably between 2 and 8% by weight relative to the total weight of the catalyst.

[0068] Preferably, the nickel-to-molybdenum molar ratio in the first catalyst is preferably between 0.1 and 0.8, preferably between 0.15 and 0.6, and even more preferably between 0.2 and 0.5.

[0069] The first catalyst also includes phosphorus as a dopant. A dopant is an added element that, in itself, has no catalytic properties but increases the catalytic activity of the active phase.

[0070] The phosphorus content in said catalyst, expressed as P2O5, is between 0.1 and 20% by weight relative to the total weight of the catalyst, preferably between 0.2 and 15% by weight, and most preferably between 0.3 and 11% by weight expressed as P2O5.

[0071] The phosphorus to molybdenum molar ratio in the first catalyst is greater than or equal to 0.05, preferably greater than or equal to 0.07, preferably between 0.08 and 1, preferably between 0.1 and 0.9 and most preferably between 0.15 and 0.8.

[0072] The first catalyst may advantageously also contain at least one dopant selected from boron, fluorine and a mixture of boron and fluorine.

[0073] When the catalyst contains boron or fluorine or a mixture of boron and fluorine, the content of boron or fluorine or a mixture of the two is preferably between 0.1 and 10% by weight expressed as boron oxide and / or fluorine element relative to the total weight of the catalyst, preferably between 0.2 and 7% by weight, and most preferably between 0.2 and 5% by weight.

[0074] The pore volume of said catalyst is generally between 0.1 cm³ / g and 1.5 cm³ / g, preferably between 0.15 cm³ / g and 1.1 cm³ / g. The total pore volume is measured by mercury porosimetry according to ASTM D4284 with a wetting angle of 140°, as described in the book Rouquerol F.; Rouquerol J.; Singh K. “Adsorption by Powders & Porous Solids: Principle, methodology and applications”, Academic Press, 1999, for example using an Autopore III™ instrument from Micromeritics™.

[0075] The first catalyst is characterized by a specific surface area of ​​between 5 and 400 m² / g, preferably between 10 and 350 m² / g, preferably between 40 and 350 m² / g, and most preferably between 50 and 300 m² / g. The specific surface area is determined in the present invention by the BET method according to ASTM D3663, a method described in the same work cited above.

[0076] The support comprises alumina, and preferably extruded alumina. Preferably, the support consists of alumina, preferably gamma alumina.

[0077] The alumina support advantageously has a total pore volume between 0.1 and 1.5 cm³.g⁻¹, preferably between 0.4 and 1.1 cm³.g⁻¹. The total pore volume is measured by mercury porosimetry according to ASTM D4284 with a wetting angle of 140°, as described in the book Rouquerol F.; Rouquerol J.; Singh K. “Adsorption by Powders & Porous Solids: Principle, methodology and applications”, Academic Press, 1999, for example using an Autopore III™ instrument from Micromeritics™.

[0078] The specific surface area of ​​the alumina support is advantageously between 5 and 400 m².g⁻¹, preferably between 10 and 350 m².g⁻¹, and more preferably between 40 and 350 m².g⁻¹. The specific surface area is determined in the present invention by the BET method according to ASTM D3663, a method described in the same work cited above.

[0079] The support is advantageously presented in the form of irregular and non-spherical beads, extrudates, pellets or agglomerates whose specific shape may result from a crushing step.

[0080] The first catalyst may further comprise an organic compound or a group of organic compounds known for their role as additives. The function of the additives is to increase the catalytic activity compared to the unadditized catalysts. More specifically, the catalyst may further comprise one or more organic compounds containing oxygen and / or one or more organic compounds containing nitrogen and / or one or more organic compounds containing sulfur. Preferably, the catalyst may further comprise one or more organic compounds containing oxygen and / or one or more organic compounds containing nitrogen. Preferably, the organic compound contains at least two carbon atoms and at least one oxygen and / or nitrogen atom, without containing any other heteroatoms.

[0081] Generally, the organic compound is chosen from a compound containing one or more chemical functions chosen from a carboxylic function, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide or compounds including a furanic ring or a sugar.

[0082] An oxygen-containing organic compound can be one or more compounds with one or more chemical functionalities, including carboxyl groups, alcohols, ethers, aldehydes, ketones, esters, or carbonates, or compounds containing a furanic ring, or sugars. An oxygen-containing organic compound is defined here as a compound containing no other heteroatoms. As an example, the oxygen-containing organic compound may be one or more chosen from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (with a molecular weight between 200 and 1500 g / mol), propylene glycol, 2-butoxyethanol, 2-(2-butoxyethoxy)ethanol, 2-(2-methoxyethoxy)ethanol, triethylene glycol dimethyl ether, glycerol, acetophenone, 2,4-pentanedione, pentanone, acetic acid, maleic acid, malic acid, malonic acid, oxalic acid, gluconic acid,tartaric acid, citric acid, γ-ketovaleric acid, a C1-C4 dialkyl succinate and more particularly dimethyl succinate, methyl acetoacetate, ethyl acetoacetate, 2-methoxyethyl 3-oxobutanoate, 2-methacryloyloxyethyl 3-oxobutanoate, dibenzofuran, a crown ether, orthophthalic acid, glucose, fructose, sucrose, sorbitol, xylitol, γ-valerolactone, 2-acetylbutyrolactone, propylene carbonate, 2-furaldehyde (also known as furfural), 5-hydroxymethylfurfural (also known as 5-(hydroxymethyl)-2-furaldehyde or 5-HMF), 2-acetylfuran, the 5-methyl-2-furaldehyde, methyl 2-furoate, furfuryl alcohol (also known as furfuranol), furfuryl acetate, ascorbic acid, butyl lactate, ethyl lactate, butyl butyryllactate, ethyl 3-hydroxybutanoate, ethyl 3-ethoxypropanoate, methyl 3-methoxypropanoate,2-Ethoxyethyl acetate, 2-Butoxyethyl acetate, 2-Hydroxyethyl acrylate, 2-Hydroxyethyl methacrylate, 1,5-Pentanediol, 3-Methyl-1,5-Pentanediol, 1,5-Hexanediol, 3-Ethyl-1,5-Pentanediol, 2,4-Diethyl-1,5-Pentanediol, 5-Methyl-2(3H)-Furanone, Butyl glycolate, Ethyl 4-Oxopentanoate, Diethyl maleate, Dimethyl maleate, Dimethyl fumarate, Diethyl fumarate, Dimethyl adipate, Dimethyl 3-Oxoglutarate, Dimethyl tartrate, Diethyl tartrate, Diisopropyl tartrate, tartrate di-tert-butyl, dimethyl malate, diethyl malate, diisopropyl malate and dibutyl malate.

[0083] The nitrogen-containing organic compound may be one or more compounds selected from among those containing one or more chemical functional groups, including either an amine or a nitrile group. Here, a nitrogen-containing organic compound is defined as a compound that does not contain any other heteroatoms. For example, the nitrogen-containing organic compound may be one or more compounds selected from the group consisting of ethylenediamine, diethylenetriamine, hexamethylenediamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, acetonitrile, octylamine, guanidine, or a carbazole.

[0084] The organic compound containing oxygen and nitrogen may be one or more compounds selected from among those having one or more chemical functional groups selected from among a carboxylic acid, alcohol, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, amide, urea, or oxime. Here, an organic compound containing oxygen and nitrogen is understood to be a compound that does not contain any other heteroatoms.As an example, the organic compound containing oxygen and nitrogen may be one or more chosen from the group consisting of 1,2-cyclohexanediaminetetraacetic acid, monoethanolamine (MEA), 1-methyl-2-pyrrolidinone, dimethylformamide, ethylenediaminetetraacetic acid (EDTA), alanine, glycine, nitrilotriacetic acid (NTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), tetramethylurea, glutamic acid, dimethylglyoxime, bicine, tricine, 2-methoxyethyl cyanoacetate, 1-ethyl-2-pyrrolidinone, 1-vinyl-2-pyrrolidinone, the 1,3-dimethyl-2-imidazolidinone, 1-(2-hydroxyethyl)-2-pyrrolidinone, 1-(2-hydroxyethyl)-2,5-pyrrolidinedione, 1-methyl-2-piperidinone, 1-acetyl-2-azepanone, 1-vinyl-2-azepanone and 4-aminobutanoic acid.

[0085] The sulfur-containing organic compound may be one or more of the compounds having one or more chemical functions chosen from a thiol, thioether, sulfone, or sulfoxide group. For example, the sulfur-containing organic compound may be one or more of the following: thioglycolic acid, 2,2'-thiodiethanol, 2-hydroxy-4-methylthiobutanoic acid, a sulfonated derivative of a benzothiophene or a sulfoxidized derivative of a benzothiophene, ethyl 2-mercaptopropanoate, methyl 3-(methylthio)propanoate, and ethyl 3-(methylthio)propanoate.

[0086] Preferably, the organic compound contains oxygen; preferably it is chosen from γ-valerolactone, 2-acetylbutyrolactone, triethylene glycol, diethylene glycol, ethylene glycol, ethylenediaminetetraacetic acid (EDTA), maleic acid, malonic acid, citric acid, acetic acid, oxalic acid, gluconic acid, glucose, fructose, sucrose, sorbitol, xylitol, γ-ketovaleric acid, a C1-C4 dialkyl succinate, and more particularly dimethyl succinate, dimethylformamide, 1-methyl-2-pyrrolidinone, propylene carbonate, 2-methoxyethyl 3-oxobutanoate, bicine, tricine, 2-furaldehyde (also known as furfural), the 5-Hydroxymethylfurfural (also known as 5-(hydroxymethyl)-2-furaldehyde or 5-HMF), 2-Acetylfuran, 5-Methyl-2-furaldehyde, ascorbic acid, butyl lactate, ethyl lactate, butyl butyryllactate, ethyl 3-Hydroxybutanoate,ethyl 3-ethoxypropanoate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-hydroxyethyl acrylate, 1-vinyl-2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, 1,5-pentanediol, 1-(2-hydroxyethyl)-2-pyrrolidinone, 1-(2-hydroxyethyl)-2,5-pyrrolidinedione, 5-methyl-2(3H)-furanone, 1-methyl-2-piperidinone, 4-aminobutanoic acid, butyl glycolate, ethyl 2-mercaptopropanoate, ethyl 4-oxopentanoate, diethyl maleate, dimethyl maleate, dimethyl fumarate, diethyl fumarate Dimethyl adipate and dimethyl 3-oxoglutarate.

[0087] When present, the total content of organic compound(s) containing oxygen and / or nitrogen and / or sulfur present in the catalyst is generally between 1 and 30% by weight, preferably between 1.5 and 25% by weight, and more preferably between 2 and 20% by weight relative to the total weight of the catalyst.

[0088] During the preparation of the catalyst requiring a drying step, the drying step(s) following the introduction of the organic compound are carried out at a temperature below 200°C so as to retain preferably at least 30%, preferably at least 50%, and most preferably at least 70% of the amount of organic compound introduced, calculated based on the carbon remaining on the catalyst. The remaining carbon is measured by elemental analysis according to ASTM D5373. Second catalyst

[0089] According to the invention, the second catalyst comprises a silica-alumina support and an active phase consisting of nickel and tungsten. The second catalyst according to the invention also comprises phosphorus as a dopant and an organic compound. It may further comprise boron and / or fluorine.

[0090] The hydrogenating function of said second catalyst, also called the active phase, consists of nickel and tungsten.

[0091] The second catalyst is characterized in that: the nickel content, expressed as NiO, is between 1.3 and 4.3 wt% relative to the total weight of the catalyst, preferably between 1.4 and 3.8 wt%, and more preferably between 1.5 and 3.4 wt%, the tungsten content, expressed as WO3, is between 17 and 31 wt% relative to the total weight of the catalyst, preferably between 18 and 30 wt%, preferably between 19 and 29 wt%, and more preferably between 20 and 26 wt%, the phosphorus content, expressed as P2O3, is preferably between 1.3 and 3.4 wt% relative to the total weight of the catalyst, preferably between 1.4 and 3.1 wt%, and most preferably between 1.5 and 2.8 wt%.

[0092] The Ni / W molar ratio is between 0.18 and 0.45 mol / mol, preferably between 0.20 and 0.43 mol / mol and even more preferably between 0.22 and 0.42 mol / mol.

[0093] The molar ratio P / W is between 0.18 and 0.45 mol / mol, preferably between 0.20 and 0.43 mol / mol and even more preferably between 0.22 and 0.42 mol / mol.

[0094] The catalyst based on an active phase consisting of nickel and tungsten in the presence of phosphorus and an organic compound, deposited on a silica-alumina support, and presenting the specific ratios between the different metals and / or phosphorus described above, exhibits by synergistic effect excellent activity and stability in hydrotreating, and in particular in hydrodeazotation (HDN) and in hydrogenation of aromatics (HDA) but also in hydrodesulfurization (HDS).

[0095] Without being bound by any particular theory, the silica-alumina support of the second catalyst would allow for the modification of the structure of the most refractory aromatic compounds (through isomerization and / or cracking reactions), making these molecules more reactive. Therefore, optimizing the content of each metal (especially tungsten, which provides a benefit in terms of hydrogenation) and phosphorus using specific ratios, combined with the silica-alumina support, increases the required HDA (hydrogenation-dependent aromatics) to increase the HDN (hydrogenation-dependent aromatics), leading to an overall improvement in catalytic performance.

[0096] The second catalyst having the specific ratios mentioned above is therefore particularly preferred when used in sequence with the aforementioned first catalyst upstream.

[0097] The second catalyst may advantageously also contain at least one dopant selected from boron, fluorine, and a mixture of boron and fluorine. When this dopant is present, its concentration is as described for the first catalyst.

[0098] The pore volume of the second catalyst is generally between 0.1 cm³ / g and 1.5 cm³ / g, preferably between 0.15 cm³ / g and 1.1 cm³ / g. The total pore volume is measured by mercury porosimetry according to ASTM D4284 with a wetting angle of 140°, as described in the book Rouquerol F.; Rouquerol J.; Singh K. “Adsorption by Powders & Porous Solids: Principle, methodology and applications”, Academic Press, 1999, for example using an Autopore III™ instrument from Micromeritics™.

[0099] The second catalyst is characterized by a specific surface area of ​​between 5 and 400 m² / g, preferably between 10 and 350 m² / g, preferably between 40 and 350 m² / g, and most preferably between 50 and 300 m² / g. The specific surface area is determined in the present invention by the BET method according to ASTM D3663, a method described in the aforementioned publication.

[0100] The support for the second catalyst is preferably made of silica-alumina.

[0101] The silica-alumina support advantageously has a total pore volume between 0.1 and 1.5 cm³ g⁻¹, preferably between 0.2 and 0.8 cm³ g⁻¹, and particularly preferably between 0.3 and 0.6 cm³ g⁻¹. The total pore volume is measured by mercury porosimetry according to ASTM D4284 with a wetting angle of 140°, as described in the book Rouquerol F.; Rouquerol J.; Singh K. "Adsorption by Powders & Porous Solids: Principle, methodology and applications", Academic Press, 1999, for example using a Micromeritics Autopore III™ instrument.

[0102] The specific surface area of ​​the silica-alumina support is advantageously between 5 and 400 m².g⁻¹, preferably between 100 and 350 m².g⁻¹, and more preferably between 200 and 300 m².g⁻¹. The specific surface area is determined in the present invention by the BET method according to ASTM D3663, a method described in the same work cited above.

[0103] The silica content in the substrate is at most 50% by weight relative to the total weight of the substrate, most often less than or equal to 45% by weight, preferably less than or equal to 40%. Preferably, the silica content in the substrate is between 10 and 50% by weight, preferably between 15 and 40% by weight, and particularly preferably between 20 and 35% by weight relative to the total weight of the substrate.

[0104] Sources of silicon are well known to those skilled in the art. Examples include silicic acid, silica in powder form or colloidal form (silica sol), and tetraethyl orthosilicate Si(OEt)4.

[0105] The silica-alumina carrier may also advantageously contain a zeolite. In this case, all sources of zeolites and all associated preparation methods known to those skilled in the art may be incorporated. Preferably, the zeolite is selected from the FAU, BEA, ISV, IWR, IWW, MEI, and UWY groups, and even more preferably, from the FAU and BEA groups, such as zeolite Y and / or beta, and particularly preferably such as zeolite USY and / or beta. When zeolite is present, its content is from 0.1 to 50% by weight relative to the total weight of the carrier, preferably from 0.1 to 10% by weight.

[0106] The support is advantageously presented in the form of irregular and non-spherical beads, extrudates, pellets or agglomerates whose specific shape may result from a crushing step.

[0107] The second catalyst according to the invention further comprises an organic compound or a group of organic compounds, the nature and quantities of which are described in the section for the first catalyst. When both catalysts comprise one or more organic compounds, these may be identical or different.

[0108] Preferably, the organic compound of the second catalyst contains oxygen; preferably, it is chosen from γ-valerolactone, 2-acetylbutyrolactone, triethylene glycol, diethylene glycol, ethylene glycol, ethylenediaminetetraacetic acid (EDTA), maleic acid, malonic acid, citric acid, acetic acid, oxalic acid, gluconic acid, glucose, fructose, sucrose, sorbitol, xylitol, γ-ketovaleric acid, a C1-C4 dialkyl succinate, and more particularly dimethyl succinate, dimethylformamide, 1-methyl-2-pyrrolidinone, propylene carbonate, 2-methoxyethyl 3-oxobutanoate, bicine, tricine, 2-furaldehyde (also known as furfural), 5-hydroxymethylfurfural (also known as 5-(hydroxymethyl)-2-furaldehyde or 5-HMF), 2-acetylfuran, 5-methyl-2-furaldehyde, ascorbic acid, butyl lactate, ethyl lactate, butyl butyryllactate,ethyl 3-hydroxybutanoate, ethyl 3-ethoxypropanoate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-hydroxyethyl acrylate, 1-vinyl-2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, 1,5-pentanediol, 1-(2-hydroxyethyl)-2-pyrrolidinone, 1-(2-hydroxyethyl)-2,5-pyrrolidinedione, 5-methyl-2(3H)-furanone, 1-methyl-2-piperidinone, 4-aminobutanoic acid, butyl glycolate, ethyl 2-mercaptopropanoate, ethyl 4-oxopentanoate, diethyl maleate, dimethyl maleate, fumarate dimethyl, diethyl fumarate, dimethyl adipate and dimethyl 3-oxoglutarate.

[0109] According to a preferred embodiment, the hydrotreating process implements a sequence of a first hydrotreating reaction section containing the first nickel-molybdenum-based catalyst in the presence of phosphorus and an organic compound on an alumina support and a second hydrotreating reaction section containing the second nickel-tungsten-based catalyst in the presence of phosphorus and an organic compound on a silica-alumina support, said second catalyst being characterized by: the nickel content, expressed as NiO, of between 1.3 and 4.3 wt% relative to the total weight of the catalyst, preferably between 1.4 and 3.8 wt%, and more preferably between 1.5 and 3.4 wt%, the tungsten content, expressed as WO3, of between 17 and 31 wt% relative to the total weight of the catalyst, preferably between 18 and 30 wt%, preferably between 19 and 29 wt%, and more preferably between 20 and 26 wt%, the phosphorus content, expressed as P2O5, preferably between 1.3 and 3.4 wt% relative to the total weight of the catalyst, preferably between 1.4 and 3.1 wt%, and most preferably between 1.5 and 2.8 wt%. a Ni / W molar ratio of between 0.18 and 0.45 mol / mol, preferably between 0.20 and 0.43 mol / mol and even more preferably between 0.22 and 0.42 mol / mol.a P / W molar ratio of between 0.18 and 0.45 mol / mol, preferably between 0.20 and 0.43 mol / mol and even more preferably between 0.22 and 0.42 mol / mol.

[0110] According to this preferred embodiment, said first hydrotreating reaction section containing the first catalyst occupies a volume V1, and said second hydrotreating reaction section containing the second catalyst occupies a volume V2, the distribution of volumes V1 / V2 being between 50%vol / 50%vol and 90%vol / 10%vol, preferably between 60%vol / 40%vol and 85%vol / 15%vol and particularly preferably between 70%vol / 30%vol and 80%vol / 20%vol, respectively of said first and second hydrotreating reaction sections.

[0111] According to this method, the organic compound is preferably chosen from γ-valerolactone, 2-acetylbutyrolactone, triethylene glycol, diethylene glycol, ethylene glycol, ethylenediaminetetraacetic acid (EDTA), maleic acid, malonic acid, citric acid, acetic acid, gluconic acid, glucose, fructose, sucrose, sorbitol, xylitol, γ-ketovaleric acid, a C1-C4 dialkyl succinate and more particularly dimethyl succinate, dimethylformamide, 1-methyl-2-pyrrolidinone, propylene carbonate, 2-methoxyethyl 3-oxobutanoate, bicine, tricine, 2-furaldehyde (also known as furfural), 5-hydroxymethylfurfural (also known as 5-(hydroxymethyl)-2-furaldehyde or 5-HMF), 2-acetylfuran, 5-methyl-2-furaldehyde, ascorbic acid, butyl lactate, ethyl lactate, butyl butyryllactate, ethyl 3-hydroxybutanoate, ethyl 3-ethoxypropanoate,2-Ethoxyethyl acetate, 2-Butoxyethyl acetate, 2-Hydroxyethyl acrylate, 1-Vinyl-2-pyrrolidinone, 1,3-Dimethyl-2-imidazolidinone, 1,5-Pentanediol, 1-(2-Hydroxyethyl)-2-pyrrolidinone, 1-(2-Hydroxyethyl)-2,5-pyrrolidinedione, 5-Methyl-2(3H)-furanone, 1-Methyl-2-piperidinone, 4-Aminobutanoic acid, butyl glycolate, ethyl 2-mercaptopropanoate, ethyl 4-oxopentanoate, diethyl maleate, dimethyl maleate, dimethyl fumarate, diethyl fumarate, dimethyl adipate, and Dimethyl 3-oxoglutarate. Preparation process

[0112] The first and second catalysts can be prepared according to any method of preparation of a supported catalyst known to those skilled in the art.

[0113] The first and second catalysts can be prepared according to a preparation process comprising the following steps: (i) a nickel precursor, a molybdenum precursor or a tungsten precursor, phosphorus when present, and an organic compound when present are brought into contact with an alumina or silica-alumina support, so as to obtain a catalyst precursor, (ii) said catalyst precursor from step (i) is dried at a temperature below 200°C, (iii) optionally, the catalyst precursor obtained in step (ii) is calcined at a temperature between 200°C and 550°C, (iv) optionally, the catalyst obtained in step (ii) or in step (iii) is sulfided.

[0114] During the contacting step (i), the first and second catalysts can be prepared by impregnating the selected support with metals and phosphorus. Impregnation can, for example, be carried out using the method known to those skilled in the art as dry impregnation, in which only the desired quantity of elements is introduced as soluble salts in the chosen solvent, for example, demineralized water, so as to fill the porosity of the support as precisely as possible.

[0115] The precursors of the active phase can be introduced simultaneously or successively. Each precursor can advantageously be impregnated in at least two stages. The different precursors can thus be advantageously impregnated successively with varying impregnation and maturation times. One of the precursors can also be impregnated in several stages.

[0116] Preferably, the precursors of the active phase are introduced simultaneously.

[0117] Nickel precursors that can be used are advantageously chosen from among nickel oxides, hydroxides, hydroxycarbonates, carbonates and nitrates, for example, nickel hydroxycarbonate, nickel carbonate or nickel hydroxide are used preferentially.

[0118] The molybdenum precursors that can be used are well known to those skilled in the art. For example, molybdenum sources include oxides and hydroxides, molybdic acids and their salts, particularly ammonium salts such as ammonium molybdate, ammonium heptamolybdate, phosphomolybdic acid (H₃PMo₁₂O₄O) and their salts, and possibly silicomolybdic acid (H₄SiMo₁₂O₄O) and its salts. Molybdenum sources can also include heteropolycompounds of the Keggin, lacunar Keggin, substituted Keggin, Dawson, Anderson, and Strandberg types, for example. Molybdenum trioxide and heteropolyanions of the Strandberg, Keggin, lacunar Keggin, or substituted Keggin types are preferred.

[0119] The tungsten precursors that can be used are also well known to those skilled in the art. For example, tungsten sources include oxides and hydroxides, tungstic acids and their salts, particularly ammonium salts such as ammonium tungstate, ammonium metatungstate, phosphotungstic acid and their salts, and possibly silicotungstic acid (H₄SiW₁₂O₄O) and its salts. Tungsten sources can also be heteropolycompounds of the Keggin, lacunar Keggin, substituted Keggin, and Dawson types, for example. Ammonium oxides and salts such as ammonium metatungstate or heteropolyanions of the Keggin, lacunar Keggin, or substituted Keggin type are preferred.

[0120] Phosphorus can be introduced in whole or in part by impregnation. Preferably, it is introduced by impregnation, preferably dry, using a solution containing nickel, molybdenum or tungsten precursors.

[0121] The phosphorus in question can advantageously be introduced alone or mixed with the active phase during any of the impregnation steps of the hydrogenating function if the latter is introduced in several stages. The phosphorus in question can also be introduced, in whole or in part, during the impregnation of an organic compound containing oxygen and / or nitrogen and / or sulfur if this compound is introduced separately from the hydrogenating function (as in the case of post- and pre-impregnation described later). It can also be introduced during the synthesis of the support, at any stage of its synthesis. Thus, it can be introduced before, during, or after the mixing of the chosen alumina gel matrix, such as, for example, and preferably, aluminum oxyhydroxide (boehmite), a precursor of alumina.

[0122] The preferred phosphorus precursor is orthophosphoric acid (H₃PO₄), but its salts and esters, such as ammonium phosphates, are also suitable. Phosphorus can also be introduced along with the VIB group element(s) in the form of Keggin, lacunar Keggin, substituted Keggin, or Strandberg-type heteropolyanions.

[0123] Any impregnation solution described in the present invention may comprise any polar solvent known to those skilled in the art. The polar solvent used is advantageously chosen from the group consisting of methanol, ethanol, water, phenol, and cyclohexanol, used alone or in mixtures. Preferably, a polar protic solvent is used. A list of common polar solvents and their dielectric constants can be found in the book "Solvents and Solvent Effects in Organic Chemistry," C. Reichardt, Wiley-VCH, 3rd edition, 2003, pages 472-474. Most preferably, the solvent used is water or ethanol, and particularly preferably, the solvent is water. In one possible embodiment, the solvent may be absent from the impregnation solution.

[0124] When the first or second catalyst further comprises a dopant selected from boron, fluorine or a mixture of boron and fluorine, the introduction of this dopant(s) can be carried out in the same manner as the introduction of phosphorus described above at various stages of preparation and in various ways.

[0125] Boron precursors can include boric acid, orthoboric acid (H₃BO₃), ammonium biborate or pentaborate, boron oxide, and boric esters. Boron can be introduced, for example, by adding a boric acid solution to a water / alcohol mixture or a water / ethanolamine mixture. Preferably, if boron is introduced, the boron precursor should be orthoboric acid.

[0126] The fluorine precursors that can be used are well known to those skilled in the art. For example, fluoride anions can be introduced in the form of hydrofluoric acid or its salts. These salts are formed with alkali metals, ammonium, or an organic compound. In the latter case, the salt is advantageously formed in the reaction mixture by the reaction between the organic compound and hydrofluoric acid. Fluorine can be introduced, for example, by impregnation with an aqueous solution of hydrofluoric acid, ammonium fluoride, or ammonium bifluoride.

[0127] The organic compound containing oxygen and / or nitrogen and / or sulfur from the second catalyst, or from the first catalyst when present, is introduced before the drying step ii). The organic compound is generally introduced by impregnation, in the presence or absence of the active phase and phosphorus and in the presence or absence of a solvent.

[0128] The introduction of the organic compound involves several implementation methods, distinguished primarily by the timing of its introduction relative to that of the metals. It can be carried out either simultaneously with the metal impregnation (co-impregnation), after the metal impregnation (post-impregnation), or before the metal impregnation (pre-impregnation), particularly during substrate preparation, and preferably during shaping or by impregnation onto a pre-formed substrate. Each method, used alone or in combination, can be performed in one or more stages.

[0129] Furthermore, the contacting step can combine at least two implementation methods, for example, co-impregnation and post-impregnation. According to an alternative embodiment, the contacting according to step i) combines at least two contacting methods, for example, co-impregnation of the active phase and phosphorus with an organic compound, followed by drying at a temperature below 200°C, and then post-impregnation with an organic compound that may be the same as or different from the one used for the co-impregnation. Each method, taken alone or in combination, can be carried out in one or more steps.

[0130] The organic compound from the second catalyst and, where present, the first catalyst, is preferably introduced post-impregnated. In this case, the metals and phosphorus are introduced first, the mixture is dried at a temperature below 200°C, the organic compound is then introduced, and the mixture is dried again at a temperature below 200°C without subsequent calcination.

[0131] The organic compound(s) is / are advantageously introduced into an impregnation solution which, depending on the method of preparation, may be the same solution or a different solution from that containing the precursors of the active phase and phosphorus, in a corresponding quantity: to a molar ratio of the organic compound to the sum of the element(s) of group VIB of the catalyst precursor(s) (Mo for the first catalyst or W for the second catalyst) of between 0.01 and 5 mol / mol, preferably between 0.05 and 3 mol / mol, preferably between 0.05 and 1.5 mol / mol and most preferably between 0.1 and 1.2 mol / mol, calculated on the basis of the components introduced in the impregnation solution(s), and to a molar ratio of the organic compound to nickel of between 0.02 and 17 mol / mol, preferably between 0.1 and 10 mol / mol, preferably between 0.15 and 8 mol / mol and most preferably between 0.6 and 5 mol / mol, calculated on the basis of the components introduced in the impregnation solution(s).

[0132] When several organic compounds are present, the different molar ratios apply to each of the organic compounds present.

[0133] Advantageously, after each impregnation step, the impregnated substrate is allowed to mature. Maturation allows the impregnation solution to disperse homogeneously within the substrate.

[0134] Each maturation step described in the present invention is advantageously carried out at atmospheric pressure, in a water-saturated atmosphere, and at a temperature between 17°C and 50°C, and preferably at room temperature. Generally, a maturation time of between ten minutes and forty-eight hours, and preferably between thirty minutes and five hours, is sufficient. Longer times are not excluded, but do not necessarily provide any improvement.

[0135] In accordance with step ii) of the preparation process according to the invention, the catalyst precursor obtained in step i) possibly matured is subjected to a drying step at a temperature below 200°C, preferably between 50 and 180°C, preferably between 70 and 150°C and most preferably between 75 and 130°C.

[0136] The drying stage is advantageously carried out by any technique known to those skilled in the art. It is advantageously carried out at atmospheric pressure or reduced pressure, and preferably at atmospheric pressure. It is advantageously carried out in a flow bed using air or any other hot gas. Preferably, when drying is carried out in a fixed bed, the gas used is either air or an inert gas such as argon or nitrogen. Most preferably, drying is carried out in a flow bed in the presence of nitrogen and / or air. Preferably, the drying stage has a short duration of between 5 minutes and 4 hours, preferably between 30 minutes and 4 hours, and most preferably between 1 hour and 3 hours.When an organic compound is present, the drying process is carried out in such a way as to preferentially retain at least 30% of the introduced organic compound, preferably greater than 50%, and even more preferably greater than 70%, calculated based on the carbon remaining on the catalyst. At the end of drying step b), a dried catalyst is obtained.

[0137] Optionally, the drying step ii) can be followed by a calcination step iii).

[0138] According to this variant, following step ii) of drying, a calcination step c) is carried out at a temperature between 200°C and 600°C, preferably between 250°C and 550°C, under an inert atmosphere (nitrogen, for example) or under an oxygen-containing atmosphere (air, for example). The duration of this heat treatment is generally between 0.5 and 16 hours, preferably between 1 and 5 hours. After this treatment, the active phase is in oxide form; the heteropolyanions are thus transformed into oxides. Similarly, the catalyst contains little or no organic compound at the time of its introduction. However, the introduction of the organic compound during its preparation increased the dispersion of the active phase, thus resulting in a more active catalyst.

[0139] When an organic compound is present, the catalyst is preferably not subjected to calcination. Here, calcination is defined as heat treatment under a gas containing air or oxygen at a temperature of 200°C or higher.

[0140] However, the catalyst precursor may undergo a calcination step before the introduction of the organic compound, particularly after the impregnation of the active phase, and phosphorus.

[0141] The first or second catalyst can be a fresh catalyst, that is, a catalyst that has not been used as a catalyst before in a catalytic unit, particularly in hydrotreating.

[0142] The first or second catalyst according to the invention may also be a regenerated and / or rejuvenated catalyst. A regenerated and / or rejuvenated catalyst is understood to be a catalyst that has been used as a catalyst in a catalytic unit, particularly in hydrotreating and / or hydrocracking, and that has undergone at least one step of partial or total coke removal, for example, by calcination (regeneration). Regeneration can be carried out by any means known to those skilled in the art. Regeneration is generally carried out by calcination at temperatures between 350 and 550°C, and most often between 400 and 520°C, or between 420 and 520°C, or even between 450 and 520°C, with temperatures below 500°C often being advantageous.

[0143] When the regenerated catalyst no longer contains sufficient active phase or phosphorus, or when its ratio(s) fall outside the preferred ratios described above, it can be rejuvenated by introducing one or more precursors of the active phase and / or phosphorus. It is also possible to introduce at least one organic compound simultaneously with the metals and phosphorus, or separately. The introduced organic compound may or may not be identical to the organic compound in the fresh catalyst when that catalyst contained such a compound. The operating conditions described above concerning maturation, drying, and optional calcination and sulfidation are, of course, applicable to this latter embodiment.

[0144] Before its use in the hydrotreating reaction, it is advantageous to transform the first and / or second catalyst into a sulfide catalyst in order to form its active species. This activation or sulfation step is carried out using methods well known to those skilled in the art, and advantageously under a sulfate-reducing atmosphere in the presence of hydrogen and hydrogen sulfide.

[0145] According to one variant, the first or second catalyst is advantageously subjected to a sulfidation step after step ii) of drying or step iii) of optional calcination.

[0146] The said catalyst is advantageously sulfurized in a way ex situ Or in situ.Sulfurizing agents include hydrogen sulfide (H₂S), elemental sulfur, CS₂, mercaptans, sulfides and / or polysulfides, hydrocarbon fractions with a boiling point below 400°C containing sulfur compounds, or any other sulfur-containing compound used for activating hydrocarbon feedstocks to sulfide the catalyst. These sulfur-containing compounds are advantageously selected from alkyl disulfides, such as dimethyl disulfide (DMDS), alkyl sulfides, such as dimethyl sulfide, thiols, such as n-butylmercaptan (or 1-butanethiol), and tertiononyl polysulfide compounds. The catalyst may also be sulfided by the sulfur contained in the feedstock to be desulfurized. Preferably, the catalyst is sulfided in situ in the presence of a sulfuric agent and a hydrocarbon feedstock. Preferably, the catalyst is sulfuric. in situin the presence of a hydrocarbon filler with added dimethyl disulfide. Application of the process according to the invention in a hydrocracking process

[0147] According to a first embodiment, the hydrotreating process according to the invention is advantageously implemented as a pretreatment in a hydrocracking process, and more particularly in a so-called "one-stage" hydrocracking process or in a so-called "two-stage" hydrocracking process. The hydrocracking process makes it possible to convert petroleum fractions, in particular vacuum distillates (VDS), into lighter and more valuable products (gasoline, middle distillates). The hydrotreating process according to the invention aims to remove sulfur, nitrogen, or aromatic compounds present in said vacuum distillate fraction.

[0148] A so-called "one-step" hydrocracking process generally begins with an advanced hydrotreatment aimed at achieving high HDN, HDS, and HDA levels in the feed before it is sent to the hydrocracking catalyst(s). This one-step hydrocracking process is particularly advantageous when the hydrocracking catalyst(s) include a support containing zeolite crystals. This advanced hydrotreatment of the feed results in only a limited conversion of the feed into lighter fractions, which remains insufficient and must therefore be supplemented by the more active hydrocracking catalyst(s).However, it should be noted that no separation of the effluents occurs between the different catalytic beds: all the effluent exiting the hydrotreating catalytic bed is injected into the catalytic bed(s) containing the hydrocracking catalyst(s), and then the products formed are separated. This version of hydrocracking has a variant that recycles the unconverted fraction to at least one of the hydrocracking catalytic beds for further feed conversion. Advantageously, the hydrotreating process according to the invention, comprising the specific sequence according to the invention, is implemented upstream of a hydrocracking catalyst in a one-stage hydrocracking process. It also allows for limiting the nitrogen content after the pretreatment stage in order to protect the zeolite-based hydrocracking catalyst, which is highly sensitive to nitrogen.

[0149] A two-stage hydrocracking process comprises a first stage which, as in the one-stage process, aims to hydrotreat the feedstock and achieve a conversion rate of generally 40 to 60%. The effluent from the first stage then undergoes separation, usually by distillation, most often called intermediate separation, which aims to separate the conversion products from the unconverted fraction. In the second stage of the two-stage hydrocracking process according to the invention, only the fraction of the feedstock not converted in the first stage is treated. This separation allows the two-stage hydrocracking process according to the invention to be more selective in terms of middle distillate (kerosene + diesel) than the one-stage process according to the invention.Indeed, the intermediate separation of the conversion products prevents their over-cracking into naphtha and gas in the second stage on the hydrocracking catalyst(s). Furthermore, it should be noted that the unconverted fraction of the feed treated in the second stage generally contains very low levels of NH3 and organic nitrogen compounds, typically less than 20 ppm by weight, or even less than 10 ppm by weight.

[0150] The first step is carried out in the presence of the specific sequence of catalysts according to the invention, and a hydrocracking catalyst, in order to perform hydrotreating and conversion generally of 40 to 60%. The catalytic beds of the specific sequence of catalysts according to the invention are advantageously located upstream of the hydrocracking catalyst. The second step is generally carried out in the presence of a hydrocracking catalyst with a composition different from that used in the first step.

[0151] Hydrocracking processes are generally carried out at a temperature between 250 and 480°C, advantageously between 320 and 450°C, preferably between 330 and 435°C, under a pressure between 2 and 25 MPa, preferably between 3 and 20 MPa, the hourly volumetric velocity of the feed relative to the volume of each catalyst (VVH) is advantageously between 0.1 and 40 h⁻¹, preferably between 0.2 and 12 h⁻¹, most preferably between 0.4 and 6 h⁻¹ and the hydrogen / feed ratio expressed in normal cubic meters (Nm³) of hydrogen per cubic meter (m³) of hydrocarbon feed is advantageously between 80 NL / L and 5000 NL / L, preferably between 100 and 2000 NL / L. Vacuum hydrocracking processes for distillates cover pressure and conversion ranges from mild hydrocracking to high-pressure hydrocracking.Soft hydrocracking is defined as hydrocracking that results in moderate conversions, generally less than 40%, and operates at low pressure, generally between 2 MPa and 6 MPa.

[0152] Hydrocracking catalysts are bifunctional: they combine an acid function with a hydro-dehydrogenating function. The acid function is provided by porous supports with surface areas generally ranging from 150 to 800 m².g⁻¹ and exhibiting surface acidity, such as halogenated aluminas (particularly chlorinated or fluorinated), combinations of boron and aluminum oxides, amorphous or crystalline mesoporous aluminosilicates, and zeolites dispersed in an oxide binder. The hydro-dehydrogenating function is provided by the presence of an active phase based on at least one metal from group VIB and possibly at least one metal from group VIII of the periodic table. The most common formulations are nickel-molybdenum (NiMo) and nickel-tungsten (NiW), and more rarely cobalt-molybdenum (CoMo). After preparation, the hydro-dehydrogenating function often appears in the form of an oxide.The usual methods for forming the hydro-dehydrogenating phase of hydrocracking catalysts involve depositing molecular precursor(s) of at least one metal from Group VIB and possibly at least one metal from Group VIII onto an acidic oxide support using the so-called "dry impregnation" technique. This is followed by maturation, drying, and calcination steps, leading to the formation of the oxidized form of the metal(s) used. Since the active and stable form for hydrocracking processes is the sulfide form, these catalysts must undergo a sulfidation step. This can be carried out within the associated process unit (in-situ sulfidation) or prior to loading the catalyst into the unit (ex-situ sulfidation). Application of the process according to the invention in an FCC process

[0153] According to a second embodiment, the hydrotreating process according to the invention is advantageously implemented as a pretreatment in a fluidized bed catalytic cracking (FCC) process. The FCC process can be carried out in a conventional manner known to those skilled in the art under suitable cracking conditions to produce lower molecular weight hydrocarbon products. A summary description of catalytic cracking (the first industrial implementation of which dates back to 1936 (HOUDRY process) or 1942 for the use of a catalyst in a fluidized bed) can be found, for example, in Ullman's Encyclopedia of Industrial Chemistry, Volume A, 18, 1991, pages 61 to 64.

[0154] A conventional catalyst comprising a matrix, possibly an additive, and at least one zeolite is typically used in the FCC process. The amount of zeolite varies but is usually 3 to 60% by weight, often 6 to 50% by weight, and most commonly 10 to 45% by weight relative to the catalyst weight. The zeolite is usually dispersed within the matrix. The amount of additive is usually 0 to 30% by weight and often 0 to 20% by weight relative to the catalyst weight. The matrix component makes up the difference to 100% by weight. The additive is generally selected from the group formed by the oxides of Group IIA metals, such as magnesium oxide or calcium oxide, rare earth oxides, and titanates of Group IIA metals.The matrix is ​​most often silica, alumina, silica-alumina, silica-magnesia, clay, or a mixture of two or more of these products. The most commonly used zeolite is zeolite Y.

[0155] Cracking is carried out in a roughly vertical reactor, either in riser or dropper mode. The choice of catalyst and operating conditions depends on the desired products and the feedstock being processed, as described, for example, in the article by M. Marcilly, pages 990-991, published in the journal of the French Petroleum Institute, November-December 1975, pages 969-1006. The process typically operates at a temperature of 450 to 600°C, with residence times in the reactor of less than one minute, often ranging from 0.1 to 50 seconds.

[0156] The pretreatment also helps to limit the nitrogen content at the end of the pretreatment stage in order to protect the zeolite-based catalytic cracking catalyst which is very sensitive to nitrogen. EXAMPLES

[0157] The following examples demonstrate the significant gain in activity in HDA and HDN using the specific sequence according to the invention.

[0158] Examples 1 to 3 describe the preparation of C1 to C3 catalysts. The final composition of each catalyst in metals and phosphorus, expressed as oxides and reported by weight of catalyst, as well as the Ni / W and P / W ratios are shown in Table 1 below.

[0159] Examples 4 to 8 describe the evaluation in hydrodeazotation (HDN) and in aromatics hydrogenation (HDA) of vacuum distillate of the different catalysts and / or chains of catalysts C1, C2 and C3. Example 1 : Preparation of the NiMoP catalyst on C1 alumina

[0160] Nickel, molybdenum, and phosphorus are added to 100 grams of an A1 alumina support exhibiting a loss on ignition of 4.1% by weight, a BET surface area of ​​263 m² / g, a pore volume measured by mercury porosimetry of 0.66 mL / g, and a mean pore diameter of 9.7 nm (defined as the median diameter by volume as measured by mercury porosimetry), and which is in extruded form. The A1 support has a water absorption volume of 0.72 mL / g. The impregnation solution is prepared by dissolving 32.9 grams of molybdenum oxide (Merck™, purity > 99.5 wt.), 10.5 grams of nickel hydroxycarbonate (Merck™, purity 99.9 wt.), and 12.78 grams of orthophosphoric acid solution (Merck™, 85 wt. in water) in 53.7 mL of distilled water at 90°C. After dry impregnation, the extrudates are left to mature in a water-saturated atmosphere for 24 h at room temperature, then dried at 90°C for 16 h.The dried, impregnated support of catalyst C1 is then treated by dry impregnation with a solution containing a mixture of dimethyl succinate (DMSU) and acetic acid (75% purity). The molar ratios are as follows: DMSU / Mo = 0.85 mol / mol, DMSU / acetic acid = 0.5 mol / mol. The catalyst undergoes a further maturation step of 3 h at 20°C in air, followed by drying in a walk-through bed oven at 120°C for 3 h. The resulting dried catalyst is designated C1. The final composition of catalyst C1, expressed as oxides, is as follows: MoO3 = 22 ± 0.2 (wt.%), NiO2 = 4.5 ± 0.1 (wt.%), and P2O5 = 5.3 ± 0.1 (wt.%). Example 2 : Preparation of the NiWP catalyst on silica-alumina C2

[0161] Nickel, tungsten, and phosphorus are added to 100 grams of an amorphous silica-alumina support ASA1, exhibiting a loss on ignition of 1.5% by weight, a BET surface area of ​​240 m² / g, a pore volume measured by mercury porosimetry of 0.46 mL / g, and a mean pore diameter of 7.42 nm (defined as the median diameter by volume as measured by mercury porosimetry), and which is in extruded form. The ASA1 support has a water absorption volume of 0.56 mL / g. The impregnation solution is prepared by dissolving 43.93 g of hydrated phosphotungstic acid (Merck™, purity >99.5 wt.), 2.97 g of phosphoric acid (Merck™, 85 wt. in water), and 7.26 g of nickel hydroxycarbonate (Merck™, purity 99.9 wt.) in 48.1 mL of distilled water at 80°C. After dry impregnation, the extrudates are left to mature in a water-saturated atmosphere for 24 h at room temperature, then dried at 120°C for 5 hours.

[0162] The dried, impregnated support of catalyst C2 is then treated by dry impregnation with a solution containing aqueous γ-ketovaleric acid. The molar ratio is: γ-ketovaleric acid / W = 0.8 mol / mol. The catalyst undergoes a further maturation step of 3 h at 20°C in air, followed by drying in a flow-through bed oven at 120°C for 3 h. The resulting dried catalyst is designated C2.

[0163] The final composition of the C2 catalyst expressed in terms of oxides is then as follows: WO3 = 25 + / - 0.2 (% by weight), NiO = 3.22 + / - 0.1 (% by weight) and P2O5 = 1.91 + / - 0.1 (% by weight). Example 3: Preparation of the NiWP catalyst on C3 alumina

[0164] Nickel, tungsten, and phosphorus are added to the same A1 support shown in Example 1. The impregnation solution is prepared by dissolving 48.18 g of hydrated phosphotungstic acid (Merck™, purity >99.5 wt.), 3.32 g of phosphoric acid (Merck™, 85 wt. in water), and 8.12 g of nickel hydroxycarbonate (Merck™, purity 99.9 wt.) in 69.4 mL of distilled water at 80°C. After dry impregnation of 100 g of the A1 support, the extrudates are left to mature in a water-saturated atmosphere for 24 h at room temperature, and then dried at 120°C for 5 hours.

[0165] The dried, impregnated support of catalyst C3 is then treated by dry impregnation with a solution containing aqueous γ-ketovaleric acid. The molar ratio is: γ-ketovaleric acid / W = 0.8 mol / mol. The catalyst undergoes a further maturation step of 3 h at 20°C in air, followed by drying in a flow-through oven at 120°C for 3 h. The resulting dried catalyst is designated C3.

[0166] The final composition of the C3 catalyst expressed as oxides is then as follows: WO3 = 27 + / - 0.2 (% by weight), NiO = 3.48 + / - 0.1 (% by weight) and P2O5 = 2.07 + / - 0.1 (% by weight). Table 1: Composition of catalysts C1, C2 and C3. Catalyst % NiO by weight % weight MoO 3 % weight WO 3 % weight P2O5 Ni / W (mol / mol) P / W (mol / mol) C1 4,5 22 - 5,3 0,38 0,46 C2 3,22 25 1,91 0,4 0,25 C3 3,48 27 2,07 0,4 0,25 Examples 4 to 7: Evaluation of the hydrodeazotation (HDN) and aromatic hydrogenation (HDA) of distillates under vacuum of catalysts or chains of catalysts C1, C2 and C3

[0167] The catalysts and / or chains of catalysts taken from among the catalysts C1, C2, C3 were tested in hydrodeazotation (HDN) and hydrogenation of aromatics (HDA) of distillates under vacuum.

[0168] The feedstock is a vacuum distillate (light vacuum gas oil according to Anglo-Saxon terminology) obtained from the deep hydroconversion of vacuum residues according to the H-Oil™ process. The characteristics of the test feedstock used are as follows: density at 15 °C = 0.92 g / cm³ (NF EN ISO 12185), refractive index at 20 °C = 1.5122 (ASTM D1218-12), sulfur content = 0.59% by weight, nitrogen content = 2720 ppm wd. • Simulated Distillation (ASTM D2887):

[0169] IP: 240.7 °C; 10%: 331.5°C; 50%: 424.9°C; 90%: 539.4°C; mp: 600.9°C.

[0170] The test is conducted in a flow-through, fixed-bed, isothermal pilot reactor, with fluids flowing from bottom to top. The reactor comprises two catalytic zones allowing for the evaluation of different sequences of catalysts C1, C2, and C3. The feed first passes through the first zone loaded with the first catalyst, then through the second zone loaded with the second catalyst.

[0171] According to example 4 (according to the invention), the first zone is loaded with catalyst C1 (70% of the volume), then the second with catalyst C2 (30% of the volume).

[0172] According to example 5 (according to the invention), the first zone is loaded with catalyst C1 (50% of the volume), then the second with catalyst C2 (50% of the volume).

[0173] According to example 6 (not in accordance with the invention), both zones are loaded with catalyst C1 (100% of the volume)

[0174] According to example 7 (not in accordance with the invention), both zones are loaded with catalyst C2 (100% of the volume).

[0175] According to example 8 (not in accordance with the invention), the first zone is loaded with catalyst C1 (70% of the volume), then the second with catalyst C3 (30% of the volume).

[0176] The catalysts are first sulfided in situ at 350°C in the pressurized reactor using an atmospheric distillation diesel feed (straight run according to Anglo-Saxon terminology) (density at 15 °C = 0.8491 g / cm 3 (NF EN ISO 12185) and initial sulfur content = 0.42 wt%), to which 2 wt% of dimethyl disulfide is added.

[0177] The catalytic tests were conducted under the following operating conditions: a total pressure of 14 MPa, a total volume of the two catalytic zones of 9 cm³, a temperature between 390°C and 415°C, with a hydrogen flow rate of 15.8 L / h and with a charge flow rate of 14.4 cm³ / h.

[0178] The characteristics of the effluents are analyzed: density at 15 °C (NF EN ISO 12185), refractive index at 20 °C (ASTM D1218-12), simulated distillation (ASTM D2887), sulfur content, and nitrogen content. Residual aromatic carbon content is calculated using the ndM method (ASTM D3238). The aromatic hydrogenation rate is calculated as the ratio of the aromatic carbon content in the feed minus the aromatic carbon content in the effluent to the aromatic carbon content in the test feed. The hydrodeazotation rate is calculated as the ratio of the nitrogen content in the effluent minus the nitrogen content in the effluent to the nitrogen content in the test feed.

[0179] The catalytic performances of the tested catalyst sequences are given in Table 2. They are expressed as relative volume activity (RVA) relative to 100% vol catalyst C1 chosen as reference (example 6), assuming an order of 1.2 for the HDA reaction and an order of 1 for the HDN reaction.

[0180] Table 2 clearly shows the gain in catalytic effect provided by the specific sequences according to the invention. Indeed, the catalyst sequences according to the invention make it possible to significantly increase the volumetric activities in the hydrodearomatization (HDA) and hydrodeazotation (HDN) reactions of the distillates under vacuum. Table 2: Related HDA and HDN activities for specific sequences according to the invention (examples 4 and 5) and non-conforming (examples 6 to 8). Example Catalyst loading into the reactor (first zone / second zone) RVA HDN RVA HDA 4 (according to the invention) 70% vol catalyst C1 + 30% vol catalyst C2 104 105 5 (according to the invention) 50% vol catalyst C1 + 50% vol catalyst C2 104 107 6 (non-compliant) 100% vol C1 catalyst 100 100 7 (non-compliant) 100% vol C2 catalyst 72 95 8 (non-compliant) 70% vol C1 catalyst + 30% vol C3 catalyst 90 101

Claims

1. Process for the hydrotreating of a hydrocarbon feedstock, at least 50% by weight of the compounds of which exhibit an initial boiling point of greater than 300°C and a final boiling point of less than 650°C, at a temperature of between 180°C and 450°C, a pressure of between 0.5 and 30 MPa, an hourly space velocity of between 0.1 and 20 h-1 and a hydrogen / feedstock ratio, expressed as volume of hydrogen, measured under standard temperature and pressure conditions, per volume of liquid feedstock, of between 50 l / l and 5000 l / l, so as to obtain a hydrotreated effluent, said process comprising the following stages: a) a first hydrotreating stage carried out in a first hydrotreating reaction section, employing at least one catalytic bed comprising at least one first hydrotreating catalyst, said hydrotreating reaction section being fed with at least said hydrocarbon feedstock and a hydrogen-comprising gas stream, said first catalyst comprising an alumina support, an active phase consisting of nickel and of molybdenum, and phosphorus and optionally an oxygen- and / or nitrogen- and / or sulfur-containing organic compound, and in which the first catalyst has a molybdenum content of between 5% and 40% by weight, expressed as MoO3, with respect to the total weight of the catalyst, a nickel content of between 1% and 10% by weight, expressed as NiO, with respect to the total weight of the catalyst, and a phosphorus content of between 0.1% and 20% by weight, expressed as P2O5, with respect to the total weight of the catalyst, b) a second hydrotreating stage carried out in a second hydrotreating reaction section, employing at least one catalytic bed comprising at least one second hydrotreating catalyst, said hydrotreating reaction section being fed with at least a part of the effluent obtained in stage a), said second catalyst comprising a silica-alumina support, an active phase consisting of nickel and of tungsten, phosphorus, and an oxygen- and / or nitrogen- and / or sulfur-containing organic compound, and in which: - the content of nickel, expressed in the NiO form, is of between 1.3% and 4.3% by weight, with respect to the total weight of the catalyst, - the content of tungsten, expressed in the WO3 form, is of between 17% and 31% by weight, with respect to the total weight of the catalyst, - the content of phosphorus, expressed in the P2O5 form, is preferably of between 1.3% and 3.4% by weight, with respect to the total weight of the catalyst, - the Ni / W molar ratio is of between 0.18 and 0.45 mol / mol, - the P / W molar ratio is of between 0.18 and 0.45 mol / mol.

2. Hydrotreating process according to Claim 1, in which said first hydrotreating reaction section containing the first catalyst occupies a volume V1 and said second hydrotreating reaction section containing the second catalyst occupies a volume V2, the distribution of the volumes V1 / V2 being of between 50% vol / 50% vol and 90% vol / 10% vol respectively of said first and second hydrotreating reaction section.

3. Hydrotreating process according to Claim 2, in which the distribution of the volumes V1 / V2 is of between 70% vol / 30% vol and 80% vol / 20% vol respectively of said first and second hydrotreating reaction section.

4. Hydrotreating process according to one of the preceding claims, in which the silica content in the support of the second catalyst is of between 10% and 50% by weight, with respect to the total weight of the support.

5. Hydrotreating process according to one of the preceding claims, in which the first catalyst additionally contains an oxygen- and / or nitrogen- and / or sulfur-containing organic compound.

6. Hydrotreating process according to one of the preceding claims, in which the organic compound is chosen from a compound comprising one or more chemical functions chosen from a carboxyl, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea or amide function or also compounds including a furan ring or also a sugar.

7. Hydrotreating process according to Claim 6, in which the organic compound is chosen from γ-valerolactone, 2-acetylbutyrolactone, triethylene glycol, diethylene glycol, ethylene glycol, ethylenediaminetetraacetic acid (EDTA), maleic acid, malonic acid, citric acid, acetic acid, oxalic acid, gluconic acid, glucose, fructose, sucrose, sorbitol, xylitol, γ-ketovaleric acid, a di(C1-C4 alkyl) succinate and more particularly dimethyl succinate, dimethylformamide, 1-methyl-2-pyrrolidinone, propylene carbonate, 2-methoxyethyl 3-oxobutanoate, bicine, tricine, 2-furaldehyde (also known under the name furfural), 5-hydroxymethylfurfural, 2-acetylfuran, 5-methyl-2-furaldehyde, ascorbic acid, butyl lactate, ethyl lactate, butyl butyryllactate, ethyl 3-hydroxybutanoate, ethyl 3-ethoxypropanoate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-hydroxyethyl acrylate, 1-vinyl-2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, 1,5-pentanediol, 1-(2-hydroxyethyl)-2-pyrrolidinone, 1-(2-hydroxyethyl)-2,5-pyrrolidinedione, 5-methyl-2(3H)-furanone, 1-methyl-2-piperidinone, 4-aminobutanoic acid, butyl glycolate, ethyl 2-mercaptopropanoate, ethyl 4-oxopentanoate, diethyl maleate, dimethyl maleate, dimethyl fumarate, diethyl fumarate, dimethyl adipate and dimethyl 3-oxoglutarate.

8. Hydrotreating process according to one of Claims 5 to 7, in which the content of organic compound is of between 1% and 30% by weight, with respect to the total weight of the catalyst.

9. Hydrotreating process according to one of the preceding claims, in which the first and / or the second catalyst is at least partially sulfur-based.

10. Hydrotreating process according to one of the preceding claims, which is carried out as pretreatment in a fluidized bed catalytic cracking process.

11. Hydrotreating process according to one of the preceding claims, which is carried out as pretreatment in a hydrocracking process.